From edb21f2e94d11d367a54f12c0b576d0ceb3f7481 Mon Sep 17 00:00:00 2001
From: vhaudiquet <vhaudiquet@localhost>
Date: Sun, 30 Aug 2026 00:22:09 +0200
Subject: [PATCH] stub: render failure dump as giant hex digits

Round 8: the Round-7 bit-band dump was visible at the L0_ADDR scanout
(both the scanout substitution and the render path work), but 32 coarse
squares per row proved unreadable from a photo. Replace the rendering
with giant hex digits: one u32 per line, 8 digits of a 3x5 font scaled
x10 (30x50 px), white on the black background depthcharge left.
Readable in any panel orientation, transcribable as text.

Same data and markers as before; word 15 still carries the raw
OVL_L0_ADDR value. Payload 10760e3c... flashed and verified.
---
 RESEARCH.md               |  15 ++++++++
 krane-fb-stub-payload.bin | Bin 159744 -> 159744 bytes
 krane-fb-stub.bin         | Bin 18912 -> 18976 bytes
 main.c                    |  73 ++++++++++++++++++++++++++------------
 4 files changed, 66 insertions(+), 22 deletions(-)

diff --git a/RESEARCH.md b/RESEARCH.md
index 5b35082..803f0ca 100644
--- a/RESEARCH.md
+++ b/RESEARCH.md
@@ -385,6 +385,21 @@ The OVL register READ is device-only (qemu -M virt aborts on reads to
 unassigned MMIO; qemu never takes the failure/substitution path, so the
 test is unaffected).
 
+## Round 8 — hex-digit diagnostic dump
+
+The bit-band dump WAS visible at the L0_ADDR scanout (proving both the
+scanout substitution and the render path), but 32 coarse squares per row
+proved unreadable from a photo, and the apparent row/column confusion
+made transcription unreliable. The dump rendering is replaced with
+**giant hex digits**: one u32 per line, 8 digits of a 3x5 cell font
+scaled x10 (30x50 px), MSB nibble first, white on depthcharge's black
+background. Readable in any panel orientation, transcribable as text.
+Same data, same markers (`0xC0DE0001` DTB stage, `0xC0DE0002|rc` LBIO
+stage, word 15 = raw OVL_L0_ADDR value).
+
+Payload `10760e3c…` flashed (cmp + vbutil OK). host_test and qemu_test
+pass.
+
 Recovery: power-cycle, boot USB (unchanged), `dd if=mmcblk0p1-pmos-backup.img
 of=/dev/mmcblk0p1 bs=4M conv=fsync`.
 
diff --git a/krane-fb-stub-payload.bin b/krane-fb-stub-payload.bin
index 866cde483c246f9ddce1cd7cecd88fcd46c551a9..7ba97d57c094486b03e666cc88a488d353cf11de 100644
GIT binary patch
delta 1301
zcmX|92~bm46umG1XJJvY2&7^)AQGVJ7;ywQh(xggwGx7{GAfG;G%f?!k%*eFprb|{
zzF<DWs0m`Lq61V}GHqFkiq^rHSW2a~4Fbxdl7Ow+0_o38?VGuC&$;K!oAVaJ=0@1u
zs%JB``<C^n+aqo*$$O={U2WeODLuGDHX3;L=ha@9iC0^9DVHaBc$(HQ4O1NVAD7;l
zoc}OUsFwVm)-zTg^Yvh%xO?v+$4?RRD+A2uUT+2P^vkH|YjX!RtBT*<ihLIKNS~UR
zl^Q%zQBuP3>XAP`QE`+zY0kFAf1_<(_uzEoA42Wr)&!G=p(%gX=re2AH<?dloh93M
ztnZR{t?{{0HdWQ2{qFiu)!BizCW#=hFR1e)$E?>e<bW*vrK;8Nw5`&j8MG%c4@qJp
zcdyZB{}^|*Ju2;iaB$~o4R+pSKUh9fn!R`JH2dxa#<wd9a(>%5W?>W**(>pToX^kM
ze=#bxV`o%mKjYFSzx9bK>Bj-jQ|jD<v)h(y?o|6{t&FJ2c%2YdV9w+3WSzgvj#76l
z<!&&~>8zZ4B(BeqrmLtomU}N!clUcds@>N1Fd`{GYh|%!oxW34o9do@vwh;?x*66B
zW3qWw19!^~?Mn~;RJ#7pEzNxvUUZ$Hzfp>v(pKv$$mWpX)1#M|*MC)w8aDSg9Uz~C
z1>KzpXjIj$UN|Msz2{-NIBiqLBoT+dSD?*FF0|@<N3*MC%RUQx5+k9);r!%XDVNUd
z*jZGQI5TEDW$CgrYYIy%eZss~#XCx4qc1!<te@_Y<Cy=0@UMu$&BYZ<RO;{jh6L}t
zGVryc<c&8aZ1cM!DVtf0SniQN01yFaS;<*0@<qu-61ITyT8%v2a9Y^?MNv{-?K(6c
z31dYx58wh!q5J<!6ibyNw16E<UIZY6>N^mUG34X9rmOZ=AjdHvdob>`(FAn0w-u4v
z1Bb6@0Ut6toysjj$h3uliC_^{21Zz;fhYwatQZ4yf$7N&zy)$EwFyUJ$pFR<P3MB8
z90)}a7!*f^y(3$*3?uN#Noxjx37~w0<?6O29X5Bk6-vFwksp#$797oFHnTrWv{E<F
z`O~HufQIhT8KQB>H2&jMLO*Fm(7*?xd;~yhqII<#Kxx|pCL0E!e1Jj^1CR<vFv+7c
zKIRaLNJQ|x^n_ya)1y{~t%=XxaKyUckif41BNVVdv*G%|>3%2o11}xXJg|K#cuKWr
z<olCz@JYZshL}82$nB|sLwG(8@pprPcM&-16gt##Pl%5Vp*ao`<AhUrg9q_VJdmV}
zJCza^kWta#Xc?m~P=s~3YQpLC?e&HCHecy`goCA<#s;Ue)^)g+H%{e!moA`nLBf9q
znz#(rw9tpKLZyqU%4FVEWlUh|Qrs}z40_WKB{G18u>u;R0ESxVaB0na(jVBmCcuXL
zX>OrbvQPqQq0X_;Dx5%|r21LNfTmF=*eDrwQ-f?IW{AX;fP)q?QpHpp2Q5ZM>KF%w
zBU^nV2Sp;JrN-URgOKKNClx?Hu`LhCZj2F%(fC_>=Hf2w(hyyBl*1hfPz}ZOKxv{q
zxzy|z+2*YKNoLKkMv*m~YtDU@J1iG#h6OJ)y&C$rV^T^ThrIEZr$*=1=f|O?Z@!W;
G=KTvyF%$^^

delta 1198
zcmY*X3rtgI6h5c7?JX~PbcjmGKwjb#0rA1ZN(BO_4Cn~P8LJ>e*i>Mdd!|=G2^J+4
z*#)Ab;1nqM!1AgNf#IB+58w)On;U5@T|v}E%8<t4-EFcg+n;<n-}%mW{>RBr>Fp@J
z-Ie76#ftY!!;kC`WsgU<H>5YZZ#rrCz~v$pLf(%n8+vutv*nj^@sl>6u*SKdU`x}t
zk=Dq2-laLiclK&-+%T@(Qd##z&g=Q|xisDP@rkNx|AVJ}=7$EKfAG>${;V~{r|8gS
zUA%kpR9RzNLuz`gVO;x4sXM?9$)lR;d3kOJGi8e8*oR#mS57#XX1t<Ttm!UmyC;vo
zE?)byWz2PJgi~gkZrXGE?E0OnMi1potch-&@yxI9D6hzR(Qh^?Y3nf<{^G?2$6MyX
zo}2wa{Q<s9B^?LKE~POg17GzqG3Vg!HrmVNLRhr(I;QH@bY@K}><Zef3xh`r>@F4h
z&etl6!ZLr5ba&*&eL8U5w2&%}eMV&TQr}Nkb>2GjXxOUTx~JTnuDlfI;Z#|5KRfI4
z#~-mvbeX2hqrrPy#Y5#whATX*g)`3a4b6?~3qO~Bvg67%OY!1&^At>rC|#*&7j!)<
zZ9OzlbNJ8Sb$5ArPp@V#v5u|`OIAkoY`m6sMlpR+Rh{DD?5Js0R;PToL%m%)x=#9`
zca^`PEpQdn;?A_beQs-3NJ-&1dD8f@p-i0mXlK&K2fl-K0at6&kIC1+6Zor1YxK$P
zp7kv<f9-s+8?$w%crBLSawl%y+VDrw_B~Ze=RzNDtK46c_TH><5UWcPHRgR85zzw!
z#_RlVehRPGt|kX&D<q`gGz#sbeguGZfKeHhF6e>Y6{|@xoxBAd?f6__e{MxaQ2SdL
zf(sJ#T)x-^;0-SRyYvZk4PqD>sHz1}d3BB;N_nxY6o-sbP)!hoW{gAaXNMb2Qsg{>
z$vT#m?OFi&dNJrIA;s_riirWL27qF+0F?eY@-A=z)lqsk9|Q3TUCKvK_gnxSK>d`^
z7WEM$a(if7M$d62l+z=8^cAS>{-Z1upr-<;`Y945Twj+P3y_xpATuX({k>-yhv4Ik
z1k_Vb)KP|%1S*$t++IMXI_rDfp7)$OCCoU&tl+e#1gS9*4w`X-O7%mDt{&zo^@O9Q
z*zfkDVt|5TC|_hCKtlje^`<v5VuRmi=u!YGCi}Rj#`L<W0EEgO;7#_uW@RD)q@1Tf
zRfb%H09NmwV`Yhmu6gLBG%w$z3UUS2t~!_eO@DD?;x@D4HOqR85n$C55-ajyh&#}#
zX4!UX>2Zd{{|`nz!?ur+oR{?Y$IK-*a||Ey4O6V_8of`5X=tFkg%~eVBgkxbrbQ&G
z(T{E-QI5N5dl3fm)B$v;2*Y`g1L!;vZa^RUf(X~5ymM59(TF9qmp$GIx;@9zi-Ahj
z7lFz^@RkxB@8>jIZsWEZa=1aeI-nSJw7&ypYQsrFLN_O&JAWwAGo<ro5=KsQUs7^G
H!VCTz8&CE#

diff --git a/krane-fb-stub.bin b/krane-fb-stub.bin
index 3dd769a49294ce8c0adc42babe13f346e83a14c8..0755eddaa9e79014b46b377fc986e8613c1984bc 100755
GIT binary patch
delta 651
zcmYjNT}V@57=GUKot?Qd^K6ObB4<i-qZ=u-AJC;iOz6V7i=d09c42rSGlJ%_oqmai
z(CLeWyl{GzQJ7e<A>oD*NQAiXu8T7=BqUbWjnF)OBcnce_?{nl{|ruv2ehXg*oFU|
ztNo84p0ic!N6M`A`WT=em_FSm`3uq1<hOa~1qS^SD}VB%lO|W@NsnE*_BaN4ZQL}2
z=XN7(970M{w5-ImY%8=!fR<$v;&r{DB+8+m=gX3tzVL$NthfNAfQfab_#4NUjcs`0
z<zeO|ANR9bOWOKR4>M<skhDXaSO<KmYEYja2pauJ84O-KaBq78dO)hzRnhZ9i56%k
z&A#)Y7AX68D=QgucI%nz*~3>I&S9nnFc?lg9opx-I|#LxgsyvEg;L*r|6u5{yaVcO
zvZyZ4n<~g?x+$aMZ9QV@7)tuO#G-df(b4XKIwqrGeA5g*Q_(S}qM@r`1{)OUEv@*T
z`6UkGV#`Hrnr7unB{qyo-v-H8$_bt@&6lk*!kM3DaG{txMDEzi1uy2$h5wl;Uf<EF
z(YA`FsZk3o@h%&SSBs*5;YwghI*DWpu$B?S^`z~34Xp7wu(cYYm-uVBlQLYjoRT#{
zkcTV@+RI4^QI2;jZpr25aivk}cJq1V7>)ByrHPE0Mr$)sj9)5wM`?b-=J3oG%n{=T
zbOtT3Uw{N&ZF#kVOIzMFAF}nh`lBNUS1&FOESz18<RgKBd~`ATHJbOkBYDSaWF<0_
IvzaY~-!U5NcmMzZ

delta 587
zcmY*VUr19?9R7ay?B45U+MI=@lr7hWS)dR7p`fNKqCliIqBke?5cy=!fhU^;E{NkP
zf<U|qL9C}RVe6qOy$C&d!H3@NQn6a}u!mrgp3Z1c9r!rE@8kP^=XZY26Y?bO4+4Ae
z&+#t*Atb|rPI0=~j)_@79C$sLFfOVDt*$2^zA%>C(3rh<|K(<aw8JdVDU}-DhcT}e
z1#WTIVB8%5e-3c>7LYx1JDo=mVp4uIV)RuK>)3k-C;;;nt9E;5*U|yJ>5+Y`gVJ)4
zb(xO;FBhz19DKfFBd#;~kOD^atf{Rbon4x78+)hRIGjoopLFebEZd{&fXS1)y<+Hl
zaeCUiG2tH9+BatBHd$ltGvmn!#S8Oj&U$QDE)!X4&j5Ebc-&rM$T1kA^AKCBA#wrv
zanN{qS$}e1DI@?ZTZB<w-chLr6IWkwh)1LYCi+IURq6^+%P2Kvw~qCT?iPsQx!_p;
zFTEh$tcD$>+BO)f9*bAWhgJPx)lq7ZADwb-`hO|T54E^qYp>l_H)~Qe5BM-vs;Jak
zS@K<@l00EvYH$dt+QgEZ4n<_xO4Ep(uwsT2m9MOm#;2%Ux6V*l9<)zUdf~c#j_9F$
t+VFu^<cPnu`~9|h<~@L5;K{=pr17q<b?MruYXv#uzqt?%{5&sut=}Nq(U$-K

diff --git a/main.c b/main.c
index bb89838..563eb0c 100644
--- a/main.c
+++ b/main.c
@@ -313,34 +313,66 @@ static void stage0(void)
 
 /* ---- failure diagnostics -------------------------------------------------
  *
- * The parse failed. Paint the failing values as bit-bands directly into
- * the live scanout buffer (read from OVL_L0_ADDR — the same buffer the
- * menu was displayed from, and the one clear_screen() blackened at
- * handoff). No parse result is needed to find it. Format: one row per
- * u32 word, 32 cells of 32x32 px, MSB first, white=1 / black=0, rows
- * every 64 px. Photograph the panel; decode offline. Word 0 is the
- * marker 0xC0DE00xx identifying the failure stage.
+ * The parse failed. Paint the failing values as giant hex digits directly
+ * into the live scanout buffer (read from OVL_L0_ADDR — the same buffer
+ * the menu was displayed from and clear_screen() blackened at handoff).
+ * No parse result is needed to find it. One word per line, 8 digits of
+ * 3x5 cells scaled x10 (30x50 px), MSB nibble first, white on the black
+ * background depthcharge left. Readable in any panel orientation.
+ * Line 0 is the marker 0xC0DE00xx identifying the failure stage.
  */
 
 #define DIAG_FB_WIDTH	1200			/* menu geometry, 32bpp xRGB */
+#define DIAG_DIGIT_SCALE	10		/* 3x5 font -> 30x50 px */
+
+static const u16 hexfont[16] = {
+	0b111101101101111, /* 0 */
+	0b010110010010111, /* 1 */
+	0b111001111100111, /* 2 */
+	0b111001011001111, /* 3 */
+	0b101101111001001, /* 4 */
+	0b111100111001111, /* 5 */
+	0b111100111101111, /* 6 */
+	0b111001001010010, /* 7 */
+	0b111101111101111, /* 8 */
+	0b111101111001111, /* 9 */
+	0b111101111101101, /* A */
+	0b100100111101111, /* b */
+	0b111100100100111, /* C */
+	0b001001111101111, /* d */
+	0b111100111100111, /* E */
+	0b111100111100100, /* F */
+};
+
+static void fill_rect(u32 base, u32 x, u32 y, u32 w, u32 h, u32 c)
+{
+	volatile u32 *fb = (volatile u32 *)(u64)base;
+	for (u32 yy = 0; yy < h; yy++) {
+		volatile u32 *row = fb + (u64)(y + yy) * DIAG_FB_WIDTH + x;
+		for (u32 xx = 0; xx < w; xx++)
+			row[xx] = c;
+	}
+}
 
 static void render_diag(u32 base, const u32 *d, int n)
 {
-	volatile u32 *fb = (volatile u32 *)(u64)base;
+	const u32 S = DIAG_DIGIT_SCALE;
 
 	for (int i = 0; i < n; i++) {
-		u32 y0 = 40 + (u32)i * 64;
-		if (y0 + 32 > 1920)
+		u32 y0 = 30 + (u32)i * 70;
+		if (y0 + 50 > 1920)
 			break;
-		for (u32 b = 0; b < 32; b++) {
-			u32 c = ((d[i] >> (31 - b)) & 1) ? 0x00FFFFFFu
-							 : 0x00000000u;
-			for (u32 yy = 0; yy < 32; yy++) {
-				volatile u32 *row = fb +
-					(u64)(y0 + yy) * DIAG_FB_WIDTH + b * 32;
-				for (u32 xx = 0; xx < 32; xx++)
-					row[xx] = c;
-			}
+		for (u32 j = 0; j < 8; j++) {
+			u32 nib = (d[i] >> (28 - 4 * j)) & 0xF;
+			u16 g = hexfont[nib];
+			u32 x0 = 40 + j * 4 * S;
+			for (u32 gy = 0; gy < 5; gy++)
+				for (u32 gx = 0; gx < 3; gx++)
+					if ((g >> (14 - gy * 3 - gx)) & 1)
+						fill_rect(base,
+							  x0 + gx * S,
+							  y0 + gy * S,
+							  S, S, 0x00FFFFFFu);
 		}
 	}
 }
@@ -363,9 +395,6 @@ static void fail_dump(u32 marker, const u32 *words, int n)
 	render_diag(l0, diag, 16);
 	halt();
 }
-
-/* ---- main checkpoint sequence ------------------------------------------- */
-
 static void checkpoint(const struct fbinfo *f, int r, int g, int b)
 {
 	fill_screen(f, mkcolor(f, r, g, b));